This invention pertains generally to electrical transmission lines and more particularly to a transmission line for carrying radio frequency power from an RF power supply to the work coil of an induction heated vapor source.
Induction heated vapor sources utilized in thin film deposition have a work coil which is energized with RF energy to produce a magnetic field which induces current in the load or succeptor and subsequently heats and vaporizes the metal to be deposited. With induction heated vapor sources of the prior art, the RF current required to vaporize materials commonly used in vapor desposition is typically on the order of several hundred amperes. A current of this magnitude requires a relatively large effective conductor, and because of the poor use factor and losses due to the so-called skin effect, i.e. the tendency of high frequency currents to be concentrated toward the outer surface of a conductor, hollow water cooled conductors are generally employed for supplying the RF current to vapor source work coils. The hollow conductors are commonly fabricated of copper, and they are expensive and difficult to use.